316 DIVISION III. ARTICULATED ANIMALS.—CLASS IV. INSECTA. 
others. These cases protect the larva against the voracity of their enemies. 
The larve have a scaly head, and the three first rings of their body are 
harder than the rest. They live in water, and breathe by means of branchi- 
ous sacs arranged on the abdomen in soft and flexible tufts. They eat 
everything that is presented to them — leaves, and even insects, and the 
larve of their own kind. The pupx are motionless. They stay about a 
fortnight in their case, whose orifice is closed by gratings of silk, then break 
through the gratings, and leave their prison. In this state they swim on 
the water until they meet with an object to which they can attach them- 
selyes, and so get out. Then they swell till they crack their skins over the 
back, when the perfect insect emerges. 
ORDER IX. HYMENOPTERA (Membrane-wings). 
The Hymenopterous insects are furnished with four membranous, naked 
wings, and a mouth with mandibles, maxillw, and two lips; the females are 
armed with a sting, placed at the extremity of the abdomen. ‘They all 
undergo a complete metamorphosis. In their perfect state they subsist on 
flowers ; their existence, including all their states, is limited to a year. 
The order is divided into two sections —the Terebrantia and Aculeata, 
in the first of which is placed the great genus 
Icnuxrumon. — As the Mammalian Ichneumon was supposed to destroy 
the crocodile by depositing its eggs in its entrails, so the Ichneumonides 
destroy the caterpillars of Lepidopterous insects, which are so injurious to 
vegetation. They deposit their eggs in or upon the bodies of naked cater- 
pillars, or pupa; and, when hatched, the larve kill their victim, and under- 
go their changes in its body. It is an extremely numerous family, there 
being not less than six thousand species. 
Cyntrs. — This genus comprises several species known as Gall Insects. 
A. globular excrescence is often observed on the leaves of the oak, called 
by children Oak Apple, and which they often eat on account of its pleas- 
ant, acid taste. This “apple” is produced by these insects, which deposit 
their eggs in the leaf, where they increase in size and consistence; in the 
mean while the excrescence grows, and becomes the temporary home of 
the larve. 
C. Galle Tinctorie produces the nutgall of commerce, which is a chief 
ingredient in the manufacture of black ink. 
Curysts. — This genus comprises the Golden-tailed Flies, which, in the 
richness of their colors, rival the gorgeous hues of the humming-birds. 
The second section of the Hymenoptera (the AcuLEATA) contains the 
well-known and remarkable genus 
